The present invention relates to a color filter and a manufacturing method therefor, and a display device and electronic equipment, and relates specifically to the colored sections of color filters.
In recent years, in electronic equipment such as notebook computers, mobile telephones and electronic organizers, display devices such as liquid crystal display devices and plasma discharge display devices have become widely used as devices for displaying information. Recently, display devices in which full color display is made possible by providing a color filter on one of the substrates have become mainstream.
A color filter is formed by arranging R (red), G (green) and B (blue) colored sections in an arrangement such as a stripe arrangement, a delta arrangement or a mosaic arrangement on the surface of a substrate made of glass or plastic or the like. There are several methods for manufacturing this color filter, which are classified into several groups according to the materials and manufacturing method used for the colored sections. But recently an inkjet method whereby a plurality of colored sections are formed on a substrate by discharging colored ink from the nozzle of an ink jet head has been proposed (see for example patent publications 1, 2 below).
1. Japanese Unexamined Patent Application, First Publication No. 2000-310706A
2. Japanese Unexamined Patent Application, First Publication No. Hei 11-248926A
Here, a method of manufacturing a color filter using a conventional ink jet method is described with reference to the drawings.
FIG. 47 to FIG. 51 are cross-sectional views showing an example of the manufacturing steps for a color filter.
First, as shown in FIG. 47, a black matrix (light shielding layer) 901 made of metal Cr or the like is formed on a substrate 900, and a resist layer 902 which covers the substrate 900 and the black matrix 901 is then formed. The black matrix 901 is formed for example, by the steps of forming a metal Cr film, forming a resist layer, performing exposure treatment, performing etching treatment, and removing the resist layer.
Next, as shown in FIG. 48, a portion of the resist layer 902 is removed by performing exposure treatment and etching treatment on the resist layer 902 to form concave sections 903. The concave sections 903 are partitioned by the substrate 900 and bank sections 904 which represent the remaining sections of the resist layer 902.
Next, as shown in FIG. 49, the R (red) colored sections 905 are formed in the concave sections 903 by discharging colored ink, which is the material which forms the colored sections, from an ink jet head which is not shown in the diagram into a portion of the concave sections 903, and then drying this colored ink.
Next, as shown in FIG. 50, in the same manner as for the R (red) colored sections 905, G (green) colored sections 906 and B (blue) colored sections 907 are sequentially formed in other concave sections 903. Because the colored sections 905, 906 and 907 are separated from other adjacent colored sections by the bank sections 904, the colored sections do not mix with each to form color mixtures.
Finally, as shown in FIG. 51, an over coat layer 908 made of an acrylic resin or an epoxy resin or the like is formed over the colored sections, to obtain the color filter.
However, in the conventional color filter shown in FIG. 51, in order to prevent the colored sections 905, 906, 907 from mixing together, the height of the bank sections 904 must be set to approximately twice the thickness of the colored sections 905, 906, 907, and consequently, a difference in level occurs between the bank sections 904 and the colored sections 905, and the presence of this difference in level makes it difficult to ensure flatness of the over coat layer 908. The over coat layer 908 eventually partitions the cell gap which supports the liquid crystal in the liquid crystal device, and consequently a reduction in the flatness of the over coat layer 908 can lead to unevenness in the spacing of the cell gap, which may adversely affect the contrast ratio or the operating voltage or the like of the liquid crystal device.
Accordingly, in order to ensure the flatness of the over coat layer 908, it is possible to form the over coat layer 908 thickly and fill in the differences in level between the bank sections 904 and the colored sections 905, but if the over coat layer 908 is thick, the overall thickness of the color filter increases, and consequently a problem occurs in that the light transmittance of the color filter is reduced, causing a reduction in the brightness of the liquid crystal device.
In addition, in conventional color filter manufacturing methods, a further problem arises in that in order to form the black matrix 901 and the bank sections 904, the exposure treatment and the etching treatment must each be performed at least twice, and as a result the manufacturing steps tend to become complex.
The present invention takes the above factors into consideration, with an object of providing a color filter which is low cost, has excellent light transmittance, is thin and has excellent flatness.
Furthermore, another object of the present invention is to provide a color filter manufacturing method in which the manufacturing steps can be simplified.
In addition, yet another object of the present invention is to provide a display device comprising an aforementioned color filter, in which there is no irregularity in the contrast ratio and operating voltage, and which has high contrast and good visibility, and to also provide electronic equipment incorporating this display device.
In order to achieve these objects, the present invention employs the following construction.
A color filter of the present invention is a color filter produced by forming a plurality of colored sections on a substrate, wherein a plurality of concave sections are formed in one surface of the substrate, an ink repellant layer is formed between adjacent concave sections, formation sections are formed by the concave sections and the ink repellant layer, and the colored sections are formed in each formation section.
According to this color filter, the colored sections are formed in formation sections partitioned by a thin walled section and the ink repellant layer, meaning that at least a portion of the colored section is embedded in the substrate, enabling the thickness of the colored section regions to be reduced, and consequently it is possible to improve the light transmittance of the color filter.
Furthermore, because at least a portion of the colored section is embedded in the substrate, differences in level between the colored sections and the ink repellant layer can be minimized, and consequently even if the over coat layer which protects the colored sections and the ink repellant layer is formed more thinly than in conventional methods, the flatness of the over coat layer can still be ensured, and the light transmittance of the color filter can be improved by reducing the thickness of the filter.
In addition, because an ink repellant layer which has colored ink repellant properties is formed around the thin walled section, when colored ink is discharged to form the colored sections, there is no danger of the discharged colored ink spreading outside the formation sections, and no danger of adjacent colored sections contacting each other and resulting in color mixing.
Furthermore, a color filter of a mode the present invention is the color filters as disclosed above, wherein at least the upper surface of the ink repellant layer has ink repellant properties, and the formation sections are formed by partitioning by the concave sections and the wall surfaces of the ink repellant layer which are continuations of the wall surfaces of the concave sections.
According to this color filter, because the upper surface of the ink repellant layer has ink repellant properties, even if the colored ink misses its target and is discharged onto the upper surface of the ink repellant layer, the colored ink does not remain on this upper surface and falls into the targeted formation sections, and consequently there is no danger of color mixing occurring between adjacent colored sections.
Furthermore, a color filter of a mode of the present invention is any one of the color filters as disclosed above, wherein the thickness t3 of the colored sections is set to a value less than the combined total (t1+t2) of the depth t1 of the concave sections and the layer thickness t2 of the ink repellant layer. The thickness t3 of the colored sections may be set to a value greater than the depth t1 of the concave sections.
According to this color filter, the thickness t3 of the colored sections is set to a value which is less than the combined total (t1+t2), which means that the colored sections are provided at a position which is lower than the upper surface of the ink repellant layer, and therefore there is no danger of the discharged colored ink overflowing from the formation sections, and there is no danger of adjacent colored sections contacting each other.
Furthermore, a color filter of a mode of the present invention is any one of the color filters as disclosed above, wherein the thickness t3 of the colored sections is set to a value which is less than the depth t1 of the concave sections.
According to this color filter, because the thickness t3 of the colored sections is set to a value which is less than the depth t1 of the concave sections, the colored sections are always formed inside the concave sections, and the colored sections do not contact the wall surfaces of the ink repellant layer, and consequently the thickness of the ink repellant layer can be even further reduced, making it possible to improve the light transmittance of the color filter by further reducing the thickness of the entire color filter.
Furthermore, a color filter of a mode of the present invention is any one of the color filters as disclosed above, wherein the ink repellant layer is made of an ink repellant transparent photosensitive resin film, and a light shielding layer is formed on the rear surface of the substrate.
The transparent photosensitive resin film functions as a photoresist, and can be processed into a desired pattern by photolithographic techniques, and can consequently be used as a pattering mask when etching the substrate. Furthermore, the transparent photosensitive resin film has excellent light transmittance, and can be adequately exposed even when the film thickness is thick.
Furthermore, a color filter of a mode of the present invention is any one of the color filters as disclosed above, wherein the ink repellant layer is a layered product of an ink repellant transparent photosensitive resin film and a light shielding film.
The transparent photosensitive resin film functions as a photoresist, and can be processed into a desired pattern by photolithographic techniques, and can consequently be used as a pattering mask when etching the light shielding film and the substrate. Furthermore, the transparent photosensitive resin film has excellent light transmittance, and can be adequately exposed even when the film thickness is thick.
Furthermore, a color filter of a mode of the present invention is any one of the color filters as described above, wherein the ink repellant layer is formed of an ink repellant black photosensitive resin film.
The black photosensitive resin film functions as a photoresist, and can be processed into a desired pattern by photolithographic techniques, and can consequently be used as a pattering mask when etching the substrate. Furthermore, this black photosensitive resin film can also be used as a light shielding layer, and consequently it is not necessary to provide a separate light shielding layer, and the thickness of the color filter can be reduced.
Next, a display device of a mode of the present invention is a display device comprising a color filter provided on one of a pair of substrates which oppose each other with a liquid crystal disposed therebetween, wherein a plurality of concave sections are formed in one surface of the substrate, an ink repellant layer is formed between adjacent concave sections, formation sections are formed by the concave sections and the ink repellant layer, and the color filter is formed of a plurality of colored sections formed in each of the formation sections.
Furthermore, a display device of a mode of the present invention is the display device comprising a color filter on one of a pair of substrates which oppose each other with a discharge display section disposed therebetween, wherein a plurality of concave sections are formed in one surface of the substrate, an ink repellant layer is formed between adjacent concave sections, formation sections are formed by the concave sections and the ink repellant layer, and the color filter is formed of a plurality of colored sections formed in each of the formation sections.
According to these display devices, because the colored sections are formed in formation sections partitioned by the concave sections provided in the substrate and the ink repellant layer, the colored sections are at least partially embedded in the substrate, and the thickness of the colored section region can be reduced, and consequently it is possible to improve the brightness of the display device by improving the light transmittance of the color filter.
Furthermore, because the colored sections are at least partially embedded in the substrate, differences in level between the colored sections and the ink repellant layer can be minimized, and consequently even if the over coat layer which protects the colored sections and the ink repellant layer is formed more thinly than in conventional methods, the flatness of the over coat layer can still be ensured, and the light transmittance of the color filter can be improved by reducing the thickness of the filter, thereby improving the brightness of the display device.
In addition, because an ink repellant layer with colored ink repellant properties is formed around the thin walled sections, when colored ink is discharged to form the colored sections, there is no danger of the discharged colored ink spreading outside the formation sections, and there is no danger of adjacent colored sections contacting each other and resulting in color mixing, meaning color bleeding can be prevented.
Furthermore, a display device of a mode of the present invention is any one of the display devices as disclosed above, wherein at least the upper surface of the ink repellant layer has ink repellant properties, and the formation sections are formed by partitioning by the concave sections and the wall surfaces of the ink repellant layer which are continuations of the wall surfaces of the concave sections.
According to this display device, because the upper surface of the ink repellant layer has ink repellant properties, even if the colored ink misses its target and is discharged onto the upper surface of the ink repellant layer, the colored ink does not remain on this upper surface and falls into the targeted formation sections, and consequently there is no danger of color mixing occurring between adjacent colored sections, meaning color bleeding can be prevented.
Furthermore, a display device of a mode of the present invention is any one of the display devices as disclosed above, wherein the thickness t3 of the colored sections is set to a value which is less than the combined total (t1+t2) of the depth t1 of the concave sections and the thickness t2 of the ink repellant layer. The thickness t3 of the colored sections may be set to a value greater than the depth t1 of the concave sections.
According to this display device, the thickness t3 of the colored sections is set to a value which is less than the combined total (t1+t2), and consequently the colored sections are provided at a position which is lower than the upper surface of the ink repellant layer, and there is no danger of the discharged colored ink overflowing from the formation sections, and there is no danger of adjacent colored sections contacting each other causing color mixing, meaning color bleeding can be prevented.
A display device of a mode of the present invention is any one of the display devices as disclosed above, wherein the thickness t3 of the colored sections is set to a value which is smaller than the depth t1 of the concave sections.
According to this display device, because the thickness t3 of the colored sections is set to a value which is smaller than the depth t1 of the concave sections, the colored sections are always formed inside the concave sections, and because the colored sections do not contact the wall surfaces of the ink repellant layer, the thickness of the ink repellant layer can be further reduced, making it possible to improve the light transmittance of the color filter by reducing the thickness of the entire color filter, and thereby further improve the brightness of the display device.
Furthermore, a display device of a mode of the present invention is any one of the display devices as disclosed above, wherein the ink repellant layer is made of an ink repellant transparent photosensitive resin film, and a light shielding layer is formed on the rear surface of the substrate.
The transparent photosensitive resin film functions as a photoresist, and can be processed into a desired pattern by photolithographic techniques, and can consequently be used as a pattering mask when etching the substrate. Furthermore, this transparent photosensitive resin film has excellent transmittance of visible light, and can consequently be formed on the light shielding layer without impairing the function of the light shielding layer.
Furthermore, a display device of a mode of the present invention is any one of the display devices as disclosed above, wherein the ink repellant layer is a layered product of an ink repellant transparent photosensitive resin film and a light shielding film.
The transparent photosensitive resin film functions as a photoresist, and can be processed into a desired pattern by photolithographic techniques, and can consequently be used as a pattering mask when etching the light shielding layer and the substrate. Furthermore, the transparent photosensitive resin film has excellent light transmittance, and can be adequately exposed even when the film thickness is thick.
Furthermore, a display device of a mode of the present invention is any one of the display devices as disclosed above, wherein the ink repellant layer is formed of an ink repellant black photosensitive resin film.
The black photosensitive resin film functions as a photoresist, and can be processed into a desired pattern by photolithographic techniques, and can consequently be used as a pattering mask when etching the substrate. Furthermore, this black photosensitive resin film can also be used as the light shielding layer, and it is consequently not necessary to provide a separate light shielding layer.
Next, an electronic equipment of the present invention comprises any one of the display devices disclosed above.
Because this electronic equipment comprises a display device described above with an excellent contrast ratio and brightness as the display section, the visibility of the display can be improved
Next, a color filter manufacturing method of the present invention comprises a step for forming an ink repellant layer on one surface of a substrate, a step for forming concave sections by patterning the ink repellant layer and etching the exposed substrate, and a step for forming colored sections by discharging colored ink into formation sections formed by the concave sections and the ink repellant layer and then drying this colored ink.
According to this color filter manufacturing method, because the formation sections are provided by etching the substrate exposed by patterning the ink repellant layer, the ink repellant layer surrounds the formation sections, and when colored ink is discharged towards these formation sections, there is no danger of the colored ink spreading outside the formation sections, and adjacent colored sections do not contact each other resulting in color mixing.
Suitable devices for etching the substrate include wet etching using an etching liquid, dry etching such as reactive ion etching, sandblasting, dicing, and laser beam machining and the like. Of these, wet etching is particularly preferred, and an aqueous solution of hydrofluoric acid or a hydrogen fluoride-ammonium fluoride mixed solution or the like can be used as the etching liquid.
Furthermore, a color filter manufacturing method of a mode of the present invention is a manufacturing method as disclosed above, wherein the ink repellant layer is formed of a transparent photosensitive resin film or a black photosensitive resin film, and a plurality of holes are formed by placing a photomask on the transparent photosensitive resin film or the black photosensitive resin film and then exposing and developing the film.
The transparent photosensitive resin film or black photosensitive resin film contains either a positive or a negative photoresist material, and can be processed into a desired pattern by photolithographic techniques, and can consequently be used as a patterning mask when etching the substrate, enabling the manufacturing steps to be simplified. Furthermore, because the black photosensitive resin film also functions as a light shielding layer, it is possible for the formation of the light shielding layer and the formation of the formation sections to be performed simultaneously by forming the plurality of holes and performing the subsequent etching of the substrate, and consequently the manufacturing steps can be further simplified.
Furthermore, a color filter manufacturing method of a mode of the present invention is any one of the manufacturing methods as disclosed above, wherein a light shielding film and a transparent photosensitive resin film are layered sequentially onto the substrate to form the ink repellant layer, a photomask is placed on the transparent photosensitive resin film and a portion of the transparent photosensitive resin film is removed by exposing and developing the transparent photosensitive resin film, and a portion of the exposed light shielding film is then etched, enabling patterning of the ink repellant layer.
The transparent photosensitive resin film contains either a positive or a negative photoresist material, and can be processed into a desired pattern by photolithographic techniques, and can consequently be used as a pattering mask when etching the light shielding film and the substrate, enabling the manufacturing steps to be simplified.
Furthermore, the formation of the light shielding film and the formation of the formation sections can be performed simultaneously by etching the light shielding film and subsequently etching the substrate, enabling the manufacturing steps to be simplified.